// // ******************************************************************** // * License and Disclaimer * // * * // * The Geant4 software is copyright of the Copyright Holders of * // * the Geant4 Collaboration. It is provided under the terms and * // * conditions of the Geant4 Software License, included in the file * // * LICENSE and available at http://cern.ch/geant4/license . These * // * include a list of copyright holders. * // * * // * Neither the authors of this software system, nor their employing * // * institutes,nor the agencies providing financial support for this * // * work make any representation or warranty, express or implied, * // * regarding this software system or assume any liability for its * // * use. Please see the license in the file LICENSE and URL above * // * for the full disclaimer and the limitation of liability. * // * * // * This code implementation is the result of the scientific and * // * technical work of the GEANT4 collaboration. * // * By using, copying, modifying or distributing the software (or * // * any work based on the software) you agree to acknowledge its * // * use in resulting scientific publications, and indicate your * // * acceptance of all terms of the Geant4 Software license. * // ******************************************************************** // // $Id: G4RPGTwoBody.cc,v 1.4 2008/05/05 21:21:55 dennis Exp $ // GEANT4 tag $Name: geant4-09-02 $ // #include "G4RPGTwoBody.hh" #include "Randomize.hh" #include "G4Poisson.hh" #include #include "G4HadReentrentException.hh" #include G4RPGTwoBody::G4RPGTwoBody() : G4RPGReaction() {} G4bool G4RPGTwoBody:: ReactionStage(const G4HadProjectile* /*originalIncident*/, G4ReactionProduct& modifiedOriginal, G4bool& /*incidentHasChanged*/, const G4DynamicParticle* originalTarget, G4ReactionProduct& targetParticle, G4bool& /*targetHasChanged*/, const G4Nucleus& targetNucleus, G4ReactionProduct& currentParticle, G4FastVector& vec, G4int& vecLen, G4bool /*leadFlag*/, G4ReactionProduct& /*leadingStrangeParticle*/) { // // Derived from H. Fesefeldt's original FORTRAN code TWOB // // Generation of momenta for elastic and quasi-elastic 2 body reactions // // The simple formula ds/d|t| = s0* std::exp(-b*|t|) is used. // The b values are parametrizations from experimental data. // Unavailable values are taken from those of similar reactions. // const G4double ekOriginal = modifiedOriginal.GetKineticEnergy()/GeV; const G4double etOriginal = modifiedOriginal.GetTotalEnergy()/GeV; const G4double mOriginal = modifiedOriginal.GetMass()/GeV; const G4double pOriginal = modifiedOriginal.GetMomentum().mag()/GeV; G4double currentMass = currentParticle.GetMass()/GeV; G4double targetMass = targetParticle.GetDefinition()->GetPDGMass()/GeV; targetMass = targetParticle.GetMass()/GeV; const G4double atomicWeight = targetNucleus.GetN(); G4double etCurrent = currentParticle.GetTotalEnergy()/GeV; G4double pCurrent = currentParticle.GetTotalMomentum()/GeV; G4double cmEnergy = std::sqrt( currentMass*currentMass + targetMass*targetMass + 2.0*targetMass*etCurrent ); // in GeV if (cmEnergy < 0.01) { // 2-body scattering not possible targetParticle.SetMass( 0.0 ); // flag that the target particle doesn't exist } else { // Projectile momentum in cm G4double pf = targetMass*pCurrent/cmEnergy; // // Set beam and target in centre of mass system // G4ReactionProduct pseudoParticle[3]; if (targetParticle.GetDefinition()->GetParticleSubType() == "kaon" || targetParticle.GetDefinition()->GetParticleSubType() == "pi") { // G4double pf1 = pOriginal*mOriginal/std::sqrt(2.*mOriginal*(mOriginal+etOriginal)); pseudoParticle[0].SetMass( targetMass*GeV ); pseudoParticle[0].SetTotalEnergy( etOriginal*GeV ); pseudoParticle[0].SetMomentum( 0.0, 0.0, pOriginal*GeV ); pseudoParticle[1].SetMomentum( 0.0, 0.0, 0.0 ); pseudoParticle[1].SetMass( mOriginal*GeV ); pseudoParticle[1].SetKineticEnergy( 0.0 ); } else { pseudoParticle[0].SetMass( currentMass*GeV ); pseudoParticle[0].SetTotalEnergy( etCurrent*GeV ); pseudoParticle[0].SetMomentum( 0.0, 0.0, pCurrent*GeV ); pseudoParticle[1].SetMomentum( 0.0, 0.0, 0.0 ); pseudoParticle[1].SetMass( targetMass*GeV ); pseudoParticle[1].SetKineticEnergy( 0.0 ); } // // Transform into center of mass system // pseudoParticle[2] = pseudoParticle[0] + pseudoParticle[1]; pseudoParticle[0].Lorentz( pseudoParticle[0], pseudoParticle[2] ); pseudoParticle[1].Lorentz( pseudoParticle[1], pseudoParticle[2] ); // // Set final state masses and energies in centre of mass system // currentParticle.SetTotalEnergy( std::sqrt(pf*pf+currentMass*currentMass)*GeV ); targetParticle.SetTotalEnergy( std::sqrt(pf*pf+targetMass*targetMass)*GeV ); // // Calculate slope b for elastic scattering on proton/neutron // const G4double cb = 0.01; const G4double b1 = 4.225; const G4double b2 = 1.795; G4double b = std::max( cb, b1+b2*std::log(pOriginal) ); // // Get cm scattering angle by sampling t from tmin to tmax // G4double btrang = b * 4.0 * pf * pseudoParticle[0].GetMomentum().mag()/GeV; G4double exindt = std::exp(-btrang) - 1.0; G4double costheta = 1.0 + 2*std::log( 1.0+G4UniformRand()*exindt ) /btrang; costheta = std::max(-1., std::min(1., costheta) ); G4double sintheta = std::sqrt((1.0-costheta)*(1.0+costheta)); G4double phi = twopi * G4UniformRand(); // // Calculate final state momenta in centre of mass system // if (targetParticle.GetDefinition()->GetParticleSubType() == "kaon" || targetParticle.GetDefinition()->GetParticleSubType() == "pi") { currentParticle.SetMomentum( -pf*sintheta*std::cos(phi)*GeV, -pf*sintheta*std::sin(phi)*GeV, -pf*costheta*GeV ); } else { currentParticle.SetMomentum( pf*sintheta*std::cos(phi)*GeV, pf*sintheta*std::sin(phi)*GeV, pf*costheta*GeV ); } targetParticle.SetMomentum( -currentParticle.GetMomentum() ); // // Transform into lab system // currentParticle.Lorentz( currentParticle, pseudoParticle[1] ); targetParticle.Lorentz( targetParticle, pseudoParticle[1] ); // Rotate final state particle vectors wrt incident momentum Defs1( modifiedOriginal, currentParticle, targetParticle, vec, vecLen ); // Subtract binding energy G4double pp, pp1, ekin; if( atomicWeight >= 1.5 ) { const G4double cfa = 0.025*((atomicWeight-1.)/120.)*std::exp(-(atomicWeight-1.)/120.); pp1 = currentParticle.GetMomentum().mag()/MeV; if( pp1 >= 1.0 ) { ekin = currentParticle.GetKineticEnergy()/MeV - cfa*(1.0+0.5*normal())*GeV; ekin = std::max( 0.0001*GeV, ekin ); currentParticle.SetKineticEnergy( ekin*MeV ); pp = currentParticle.GetTotalMomentum()/MeV; currentParticle.SetMomentum( currentParticle.GetMomentum() * (pp/pp1) ); } pp1 = targetParticle.GetMomentum().mag()/MeV; if( pp1 >= 1.0 ) { ekin = targetParticle.GetKineticEnergy()/MeV - cfa*(1.0+normal()/2.)*GeV; ekin = std::max( 0.0001*GeV, ekin ); targetParticle.SetKineticEnergy( ekin*MeV ); pp = targetParticle.GetTotalMomentum()/MeV; targetParticle.SetMomentum( targetParticle.GetMomentum() * (pp/pp1) ); } } } // Get number of final state nucleons and nucleons remaining in // target nucleus std::pair finalStateNucleons = GetFinalStateNucleons(originalTarget, vec, vecLen); G4int protonsInFinalState = finalStateNucleons.first; G4int neutronsInFinalState = finalStateNucleons.second; G4int PinNucleus = std::max(0, G4int(targetNucleus.GetZ()) - protonsInFinalState); G4int NinNucleus = std::max(0, G4int(targetNucleus.GetN()-targetNucleus.GetZ()) - neutronsInFinalState); if( atomicWeight >= 1.5 ) { // Add black track particles // npnb: number of proton/neutron black track particles // ndta: number of deuterons, tritons, and alphas produced // epnb: kinetic energy available for proton/neutron black track // particles // edta: kinetic energy available for deuteron/triton/alpha particles G4double epnb, edta; G4int npnb=0, ndta=0; epnb = targetNucleus.GetPNBlackTrackEnergy(); // was enp1 in fortran code edta = targetNucleus.GetDTABlackTrackEnergy(); // was enp3 in fortran code const G4double pnCutOff = 0.0001; // GeV const G4double dtaCutOff = 0.0001; // GeV // const G4double kineticMinimum = 0.0001; // const G4double kineticFactor = -0.010; // G4double sprob = 0.0; // sprob = probability of self-absorption in heavy molecules if( epnb >= pnCutOff ) { npnb = G4Poisson( epnb/0.02 ); if( npnb > atomicWeight )npnb = G4int(atomicWeight); if( (epnb > pnCutOff) && (npnb <= 0) )npnb = 1; npnb = std::min( npnb, 127-vecLen ); } if( edta >= dtaCutOff ) { ndta = G4int(2.0 * std::log(atomicWeight)); ndta = std::min( ndta, 127-vecLen ); } if (npnb == 0 && ndta == 0) npnb = 1; AddBlackTrackParticles(epnb, npnb, edta, ndta, modifiedOriginal, PinNucleus, NinNucleus, targetNucleus, vec, vecLen); } // // calculate time delay for nuclear reactions // if( (atomicWeight >= 1.5) && (atomicWeight <= 230.0) && (ekOriginal <= 0.2) ) currentParticle.SetTOF( 1.0-500.0*std::exp(-ekOriginal/0.04)*std::log(G4UniformRand()) ); else currentParticle.SetTOF( 1.0 ); return true; } /* end of file */